Add unit tests for compare256 variants.

diff --git a/test/test_compare256.cc b/test/test_compare256.cc
new file mode 100644 (file)
index 0000000..3f0673e
--- /dev/null
+++ b/test/test_compare256.cc
@@ -0,0 +1,75 @@
+/* test_compare256.cc -- compare256 unit tests
+ * Copyright (C) 2022 Nathan Moinvaziri
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+extern "C" {
+#  include "zbuild.h"
+#  include "zutil_p.h"
+#  include "cpu_features.h"
+}
+
+#include <gtest/gtest.h>
+
+#define MAX_COMPARE_SIZE (256)
+
+/* Ensure that compare256 returns the correct match length */
+static inline void compare256_match_check(compare256_func compare256) {
+    int32_t match_len, i;
+    uint8_t *str1;
+    uint8_t *str2;
+
+    str1 = (uint8_t *)zng_alloc(MAX_COMPARE_SIZE);
+    ASSERT_TRUE(str1 != NULL);
+    memset(str1, 'a', MAX_COMPARE_SIZE);
+
+    str2 = (uint8_t *)zng_alloc(MAX_COMPARE_SIZE);
+    ASSERT_TRUE(str2 != NULL);
+    memset(str2, 'a', MAX_COMPARE_SIZE);
+
+    for (i = 0; i <= MAX_COMPARE_SIZE; i++) {
+        if (i < MAX_COMPARE_SIZE)
+            str2[i] = 0;
+
+        match_len = compare256(str1, str2);
+        EXPECT_EQ(match_len, i);
+
+        if (i < MAX_COMPARE_SIZE)
+            str2[i] = 'a';
+    }
+
+    zng_free(str1);
+    zng_free(str2);
+}
+
+#define TEST_COMPARE256(name, func, support_flag) \
+    TEST(compare256, name) { \
+        if (!support_flag) { \
+            GTEST_SKIP(); \
+            return; \
+        } \
+        compare256_match_check(func); \
+    }
+
+TEST_COMPARE256(c, compare256_c, 1)
+
+#ifdef UNALIGNED_OK
+TEST_COMPARE256(unaligned_16, compare256_unaligned_16, 1)
+#ifdef HAVE_BUILTIN_CTZ
+TEST_COMPARE256(unaligned_32, compare256_unaligned_32, 1)
+#endif
+#if defined(UNALIGNED64_OK) && defined(HAVE_BUILTIN_CTZLL)
+TEST_COMPARE256(unaligned_64, compare256_unaligned_64, 1)
+#endif
+#endif
+
+#if defined(X86_SSE2) && defined(HAVE_BUILTIN_CTZ)
+TEST_COMPARE256(unaligned_sse2, compare256_unaligned_sse2, x86_cpu_has_sse2)
+#endif
+#if defined(X86_AVX2) && defined(HAVE_BUILTIN_CTZ)
+TEST_COMPARE256(unaligned_avx2, compare256_unaligned_avx2, x86_cpu_has_avx2)
+#endif